The purpose of this study is to investigate the possible efficacy and safety of new compounds applied to the treatment of certain disorders of movement, and to employ drugs as tools to analyse the physiological and pharmacological mechaaisms mediating various motor deficits. The diseases studied have included Parkinsonism, Shy Drager (SD) syndrome and the Steele-Richardson-Olzewski (SRO) syndrome. The major conclusions deriving from observations over the last year are: -(1) tetrahydrobiopterin, the cofactor for tyrosine hydroxylase, is significantly and substantially decreased in the cerebrospinal fluid of patients with idiopathic Parkinsonism, compared to age matched controls; (2) there is pharmacological evidence for damage to both presynaptic and postsynaptic components of dopaminergic pathways in the CNS of patients with SD and SRO syndromes; (3) there is a reduction of norepinephrine in the CSF in the SD syndrome; (4) dopaminergic therapy is occasionally beneficial in both SD and SRO syndromes; (5) certain neurophysiological features currently attributed to Parkinsonian pathology are also seen in elderly normal subjects.